Snoring can be defined as noisy respiratory sounds while sleeping. People who snore do not usually make snoring sounds when breathing awake in the same posture that is associated with snoring when asleep. That is because the awake person has conscious control of various muscles whose mechanical action tenses and shapes the upper airway so as to prevent the vibrations that cause snoring to occur. During sleep, the motor neurons that control most skeletal muscles are inhibited from sending commands to activate those muscles. The resulting flaccid muscle tone permits soft tissue to sag into the airway and consequently snoring to occur.
Snoring may also occur because the airway is constricted, creating turbulence, and/or when the soft tissues are unusually large, soft and easily vibrated. Snoring is particularly common and severe in males, older people, and obese people, but it can occur in virtually anyone. Predisposing factors include obesity with accumulation of adipose tissue in the airway and congenital narrowing of the upper airway. Snoring may occur in any position but is most pronounced when sleeping in a supine position in which gravity causes soft tissues to fall against the back of the airway.
The sounds of snoring are generated by vibration of soft tissues in the upper airway, such as the soft palate, uvula, tongue, lips, posterior and lateral pharyngeal wall and epiglottis. However, the soft palate and uvula are most commonly implicated.
Many treatments for excessively loud snoring have been proposed, but few are in common use because of various disadvantages and limitations in effectiveness. Treatments include mechanical devices to control body posture, mechanical appliances worn in the mouth and on the jaw, electrical stimulators applied to the mucosa of the oral cavity, surgical remodeling of the oropharynx, sound detectors to awaken the offending snorer, and acoustic cancellation techniques to reduce the sounds heard by companions. Many of these techniques have only limited effectiveness or are applicable only to certain sources of snoring. Those that are effective have various disadvantages that include physical discomfort, interference with the normal sleep of the patient and reoccurrence of snoring over time.
Muscles can be electrically stimulated artificially to contract directly or indirectly by activating the neurons that innervate them. Such stimulation has been applied to reanimate paralyzed limbs, but it has not been feasible to apply to oropharyngeal muscles with the previously available technologies. Stimulation of limb muscles has been accomplished by applying transcutaneous electrodes to the surface of the skin, by inserting percutaneous wires into the muscles and by surgically implanting electrodes in or on muscles and nerves, which electrodes are connected by leads to a central stimulus pulse generator similar to a cardiac pacemaker. More recently, wireless microstimulators have become available that are small enough to be injected into the body where they receive electrical power and/or command signals by inductive coupling from a radio-frequency electromagnetic field generated outside the body.
The muscles of the oropharynx and their motor nerves are small and difficult to access surgically. Electrical stimulation pulses applied to the muscles transcutaneously via the mucosa of the oropharynx causes unpleasant sensations as a result of activation of its many sensory nerve endings.
While snoring may not wake the subjects themselves, it is often very problematic because the noise disturbs the sleep of others in the vicinity, such as a spouse or roommate. Therefore, effective methods and devices for the treatment of snoring are desirable.